Like some sea monster that destroys an entire harbor in its death throes, Yahoo’s patent fight may end up targeting open source infrastructure technologies such as memcached and the those used by the Open Compute movement. Or maybe it’s just trying to join the Open Compute party and figured a veiled threat might be the best way. Sarah Lacey picked up the news from Facebook’s revised S-1 yesterday afternoon, and while she portrays it as a giant troll lurking behind an innocent little girl, the other side isn’t in the story at all.

I know Yahoo is in a mess of trouble — what with patent trolling, a lying CEO and its stock in the toilet — but it’s a particularly bizarre move to go after technologies that your company directly benefits from. Yahoo, for example uses memcached, likely a version that has evolved over time thanks to the alleged infringement. Yes, patent trolls go after widely adopted technologies with an eye toward profit, but in this case it’s like Yahoo is putting a gift horse on notice that it may shoot it in the mouth.

So what does Yahoo want here? This isn’t a posture that will win it any friends. Without seeing the letter or getting a comment from Yahoo (I’ve reached out), this story feels incomplete. Here’s what we know so far. From the Facebook S-1, at the tail end of a section about Facebook’s ongoing patent fight with Yahoo:

For example, we received a letter dated April 23, 2012 from Yahoo indicating that they believe 16 patents they claim to hold “may be relevant” to open source technology they allege is being used in our data centers and servers. Yahoo has not threatened or initiated litigation with respect to matters described in this letter but it may do so in the future.

Yahoo’s letter takes aim not just at Facebook but at open source and energy-efficient green technologies developed and employed by countless innovative, forward-thinking companies and engineers. We’re defending vigorously against Yahoo’s current lawsuit, and would likewise do so against any new assertion.

This put Facebook in the cape defending against the machinations of the evil troll, but given Yahoo’s history in developing and open sourcing technologies that underlie the physical infrastructure of the web, it seems odd that it would suddenly reverse positions. Perhaps this is a negotiating ploy for a cross license that Facebook is spinning into drama, but I’m curious to see what’s going on here.